Jet deflector having curved guide wall for aircraft



1956 P. F. ASH-WOOD ET AL 2,770,095

JET DEFLECTOR HAVING CURVED GUIDE WALL FOR AIRCRAFT Filed May 25, 1955 2She'ets-Sheet l Inven ors 1956 P. F. ASHWOOD ET AL 2,770,095

JET DEFLECTOR HAVING CURVED GUIDE WALL FOR AIRCRAFT Filed May 25, 1955 2Sheets-Sheet 2 iinited States Patent JET DEFLECTOR HAVING CURVED GUIDEWALL FOR AIRCRAFT Peter Frederick Ashwood, Farnham, and Philip JohnFletcher, Farnborough, England, assignors to Power Jets (Research andDevelopment) Limited, London, England, a British company Application May25, 1953, Serial No. 357,117

Claims priority, application Great Britain May 30, 1952 9 Claims. (Cl.60-3554) When a high speed jet-propelled aircraft is landing, it isdesirable to reduce the landing speed to a minimum by defecting the jetto destroy the propulsive thrust. It may also be desirable to deflectthe jet downwards towards the ground to produce an upthrust on theaircraft to compensate for loss of lift due to reduction of speed andfurthermore it may be desirable to be able to deflect the jet throughvarious angles, to give some desired combination of partial forwardthrust and partial upthrust.

The present invention makes use of the fact that a stream of fluidemerging from the open end of a duct having one side wall extendingbeyond the orifice as'a guide and curved away from the axis of the ductcan be caused to follow a path along said curved wall by setting up, atthe orifice, a pressure gradient across the stream from a minimum on theguide wall to a maximum at the free surfiace of the emerging stream.Thus according to the invention a nozzle unit has such a curved guidingside wall extending beyond the nozzle orifice on that side of the nozzletowards which it is desired to deflect the jet, in combination withmeans operable at will to cause the issuing jet to follow, or to preventit from following, the curvature of said guide wall into a pathtransverse to the direction of the nozzle. In particular the said meanscan set up or destroy a pressure gradient across the stream.

The guide wall or at least some part thereof may be pivoted or hingedfor movement to different positions. In particular there may be anelement on said curved wall but movable from a position in which itguides the jet in the undeflected direction or otherwise separates thejet from the curved wall to one in which it leaves the jet free tofollow the curvature of the said curved wall. Thus the curved wall mayhave a part which is cylindrical about an axis extending across thenozzle and projecting into the jet to eonstrict it and thus produce thepressure gradient, and said movable element may be a tangentialprojection from said cylinder movable about the axis of the cylinder.Alternatively the movable element may be a retractable projection fromthe guide wall.

The invention is illustrated by the accompanying drawings, of which:

Fig. 1 is a view of a nozzle unit in longitudinal crosssection;

Fig. 2 is an external side elevation of the same unit;

Fig. 3 is a view looking on Fig. 1 or Fig. 2 from the rear, in thedirect-ion of the arrow A of Fig. 1;

Fig. 4 is an enlarged View of a portion of the deflector;

Fig. 5 is a view corresponding to Fig. 1 of a modification.

In the construction shown in Figs. 14 the connector pipe 1, flanged forattachment to the rear of the jet pipe of a jet engine, changesprogressively in internal section rearwardly from a circular to arectangular section.

ice

tached to the rear of this pipe is the nozzle member 2 terminating in arectangular rear jet orifice. This member 2 is bounded on four sides bywalls 2a, 2b, 2c, and 2d. The wall 2a on the unde:rsidei.e. the side towhich the jet is to be deflectedis curved at 2e to semi-cylindricalshape, the axis of the cylinder lying across the width of the nozzle.The opposite wall 2b is straight and terminates substantially oppositethe nearest point of the semi-cylinder. The rectangular nozzle orificefrom which the jet will emerge is formed between the crest of wall 2eand the end of wall 2b, and is of a width of about eight times itsdepth, or even more. Side plates 20 and 2d extend beyond the otherplates, as shown, to a distance beyond the orifice at least equal to thedepth of the orifice.

The arrangement so far described could cause a jet issuing from theorifice to follow the curvature of the rear quadrant of the wall part 22as a guide, and so turn through substantially as described below. Toprevent this deflection, a movable guide flap 3 is provided forseparating the jet from the curved guiding wall 2e; this flap 3 is inthe form of a thin plate extending from Wall 2c to wall 2d andprojecting smoothly tangentially or substantially tangentially from thesemi-cylindrical wall.

Fig. 4 is an enlarged detail which shows the curved wall 2e and thetapering of the guide flap 3 at 3a adjacent to the curved wall so thatit merges into this wall, which it may rub against, or may pass withsmall clearance as the flap turns around the axis of the cylinder. Forrotating the guide flap 3, the latter is provided at each end withintegral radial arms 3b. Crank arms 4 and 5 extending parallel to thearms 3b are mounted for turning about the cylinder axis in bearings 6carried on the outside of each of the walls 26 and 2d, the outer ends ofarms 4 and 5 having projections 4a and 5a making rigid drivingconnections fitting in slots in the outer ends of the arms 3b. The crankarm 4 is a bell-crank having an arm 41) Linked to the hydraulic or otheractuator 7-pivoted in usual manner on the bracket 8 on the member 1forturning the crank arm 4 and hence the guide flap 3 through about 90.

An advantage of this construction as compared with possibly making thecurved wall 26 a complete hollow cylinder, with end discs, and with theradially'projecting guide flap 3 a fixed part thereof, the whole beingrotatable about the cylinder axis between the walls 20 and 2d, is thereduction of space and of leakage problems.

For normal flight the guide flap 3 is as shown in Fig. l or in fulllines in Fig. 4. The jet flowing through the nozzle flows over a quartercylindrical surface formed by part of the wall part 2e as it emergesfrom the jet orifice, but it follows the flat surface of the flap 3 andcontinues in the same general rearward direction. The jet thus producesa forward thrust. When it is desired to reduce the forward propulsivethrust and introduce an upthrust component, the guide flap 3 is turnedabout its axis of rotation to tilt downwardly. It is then found that ajet at subsonic speed, as it moves clear of the upper wall 2b andemerges into the atmosphere, will flow over rather more than the quartercylindrical surface on to the downwardly inclined flat surface of theflap 3 and will then leave the curved surface tangentially, therebybeing deflected downwardly to produce an upwardly inclined reaction. Byturning the flap 3 through 90 to the position shown in chain lines inFig. 4 the jet can be deflected downwardly to produce substantially onlyupthrust.

Consider conditions when the guide flap 3 is in the latter position. Thejet flowing through the nozzle will be constricted, as it comes to thejet orifice, by the curved wall part 2e. Accordingly the velocity, atleastifit be adjacent to the wall 2e and the pressure there will bedecreased. In this way a pressure gradient will be set up across thestream; the maximum eflect occurs just as the jet is emerging from theorifice, when the pressure on the top free surface of the stream issubstantially atmospheric and the pressure in the layer in contact withwall la is well below atmospheric. Due to this difference of pressurebetween the two sides of the stream the jet will be deflected towardsthe low pressure side and will follow the curvature of the curved wall.

Any destruction of the pressure gradient, either by preventing theunsymmetrical constriction of the jet or by separating the jet streamfrom the curved wall and so allowing the pressure adjacent to that wallto become atmospheric pressure, will prevent this deflection of the jet.It seems that the guide flap 3 separates the stream from the wall part2e and, by letting air in, brings the pressure below the jet stream upto atmospheric pressure; the jet will accordingly continue in Whateverwas its instantaneous direction when it was separated from the curvedwall. The extension of walls 20 and 2d 'beyond the orifice preventsatmospheric air from entering sideways and causing premature separation.

Although each nozzle orifice should have a width equal to several timesits depth, the ratio of total width to depth of the complete nozzle unitcan be considerably reduced by dividing the rear of the nozzle intoseparate passages, one above another. Such a modification is shown insection in Fig. 5 in which the connecting pipe 11, which reduces fromcircular to rectangular cross section, discharges into separate nozzles14 and 24 each of which is bounded by similar side walls to the nozzle 4of Figs. 1-3 and each of which is provided with the movable guide flap 3as in those figures. The line joining the pivot axes of these movableelements 3 lies obliquely across the nozzle unit, sloping forwardly anddownwardly at about 45; due to this stagger the guide flaps 3, whenmoved to point downwardly, will lie along spaced parallel lines so thatthe jet will be deflected in non-interfering layers.

When there is a single nozzle unit in an aircraft, it is so located inthe aircraft that when the jet is deflected downward the line of actionof the upthrust passes through or very near to the centre of gravity.When there are several units they are so disposed about the centre ofgravity that the resultant upthrust passes through it or very nearthereto.

When the deflector device is used during landing of the aircraft thethrottle is first closed to'reduce the fuel supply to the power unit andso initiate speed reduction; the guide flap, or each guide flap, isrotated, possibly only gradually, from the rearward-guiding position tothe position in which the jet is fully deflected downwards, after whichthe throttle is re-opened to give full jet upthrust. There may be asingle operating member to close the throttle during the first part ofits movement, then effect the guide vane rotation, and finally, duringthe last part of its movement, re-open the-throttle. If however it isdesired to be able to re-open the throttle to get full jet thrust in anoblique direction the throttle and the guide vane actuator arepreferably independ ently controlled.

What we claim is:

l. A jet nozzle unit for a jet propelled aircraft, for directing the jetrearwardly or deflecting the jet and comprising walls constituting anozzle, and defining a nozzle orifice discharging to atmosphere, aguiding boundary wall extending outside the nozzle beyond the saidnozzle orifice to form a smooth continuation of that one of said nozzlewalls which is on that side of the nozzle towards which it is desired todeflect the jet, said guiding wall curving round into a directiontransverse to the direction of the nozzle walls, and means operable" atwill to cause the issuing jet to separate from said guiding wall or tofollow the curvature of said guiding Wall into a path transverse to thedirection of the nozzle walls.

2. A jet nozzle unit according to claim 1 comprising, in engagement withand forming part of said curved guiding wall outside the nozzle, anelement for separating the jet from the said wall, and means for movingsaid element around the curvature of said curved wall to a position inwhich it leaves the jet free to follow at least part of the curvature ofsaid curved guiding wall.

3. A jet nozzle unit for a jet propelled aircraft, for directing the jetrearwardlyjof deflecting the jet and comprising walls constituting anozzle and defining a nozzle orifice discharging to atmosphere, aguiding boundary wall outside the nozzle extending beyond the saidnozzle orifice to form a smooth continuation of that one of the saidnozzle Walls" which is o'nthat side of the nozzle towards which it isdesired to deflect the jet, said guiding wall curving round into adirection transverse to the direction of the nozzle walls, aridmeansoperable at will to set up and destroy a pressure gradient across thejet stream where it issues through said nozzle orifice, by varying thepressure in the jet stream where it is in contact with the said wallonthe said side of the nozzle, to and from a value below the pressure onthe free surface of the jet stream issuing from the said nozzle orifice.

4. A jet nozzle unit for a jet-propelled aircraft, for directing the jetrearwardly or deflecting the jet and comprising a nozzle, means forminga partly curved guiding boundary wall outside the nozzle, extendingbeyond the nozzle orifice and on that side of the nozzle towards whichit is desired to deflect the jet, means inside the nozzle forconstricting the jet at the orifice and from the said side of the nozzleadjacent to the said outside curved guiding wall, the fluid pressure inthe jet on that side beingaccordingly reduced and a pressure gradientset up across the jet stream at the orifice by virtue of the saidconstriction, and means operable at will to destroy said pressuregradient.

5. A jet nozzle unit according to claim 4 wherein the said means fordestroying the pressure gradient consists of a movable element onsaid'cu'rved guiding wall for separating the jet from said wall at achosen point thereon, and means for moving said element around thecurvature of said curved guiding wall.

6. A'jet nozzle unit for a' jet-propelled aircraft, for directing thejet rearwardlyor deflecting the jet and comprising a' nozzle, and meansforming'a guiding boundary Wall extending beyondthe nozzle orifice onthat side of the nozzle towards which it is desired to deflect the jet,which wall has asurface partly cylindrical about an axis extendingacross the nozzle at the nozzle discharge orifice and which projectsinto the issuing jet path to constrict the jet, at the orifice, incombination with a movable'element for separating'the jet from thecylindrical surface of said guiding wall'at a chosen point rearward ofthe orifice.

7. A jet nozzle unit according to claim 6 wherein the said jetsepai-ating elenient comprises amovable element forming a tangentialprojection from the saidcyli'ndrical' surface in conibinatiori withmeans'for moving said ele ment about the axis of the cylinder topositio'ns Whereit points tangentially from the cylindrical surface indifferent directions according to how it is required to direct theissuing jet. l

8. A jet no'zzlun'it acc'ordirig "t'o clairri 7 wherein" saidcylindrical guiding wall is fixed andin whichsaid'movahle tangentiallyprojecting element is movable relatively to the cylindrical surfaceabout the axis thereof.

9. A jet nozzle unit for a jet propelled aircraft, for directing'the jetrearwardly or deflecting the jet and comprising walls con'stitutinga'plurality of' nozzles, and defining a plurality of shallowelongatednozzle orifices discharging to atmosphere, one above die other,each said orifice except the lowest being at some distance to theReferences Cited in the file of this patent rearof the orificeimmediately beneath it, a plurality of UNITED STATES PATENTS guidingboundary walls outside the nozzles, forming a smooth continuation ofeach one of the first said walls 2418488 Th(.)mpson 1947 defining thelower boundary of a nozzle orifice and eX- 5 10 195,0 tending beyond theorifice, said guiding boundary walls 2637164 Robbon et a1 May 1953curving smoothly from the rearward to the downward FOREIGN PATENTSdirection to define a numb-er of downward paths, one

behind the other, and means operable at will to cause the 4322 GreatBntam 1876 issuing jet to separate from each said guiding wall and 10272464 swltzerland 1951 continue rearwardly, or to follow the curvatureof each said guiding wall into a number of parallel downward paths.

